The present invention relates to a mounting for gas turbine engines, and in particular, to a trunnion mounting arrangement for aircraft mounted gas turbine engines.
It is often desirable to mount aircraft gas turbine engines to surrounding support structures by means of a pair of laterally disposed trunnions.
In known arrangements the trunnion mounting members typically connect the engine casing to the supporting structure in a single plane transverse to the engine axis. Usually the trunnions support the engine about its center of gravity and as such are typically connected directly to a central section of the engine's casing.
Unfortunately problems associated with engine case distortion can arise in engines mounted this way. When the trunnion members are connected directly to the engine casing, the shear forces and bending moments acting on the engine casing due to engine weight, typically act to deflect the engine casing in the same sense. When the engine casing is subject to substantial vertical "g" loads, for example during aircraft manoeuvres, this characteristic can lead to significant casing distortion and rotor tip rubs.
Obviously problems such as these could be overcome at the expense of engine weight simply by increasing the thickness of selective sections of engine casing.
However, as with all aircraft related components such casings are designed to be of relatively lightweight construction compared with non-aircraft structures subject to similar loadings.
In mounting gas turbine engines it is, therefore, necessary to give careful consideration to the manner in which engine loads are transferred to the supporting structure; and with regard to engine case distortion in particular, it is necessary to consider the manner in which the supporting structure reacts the loads into the engine casing.
Accordingly, it is an objective of the present invention to provide a trunnion mounting arrangement for a gas turbine engine which reduces engine casing distortions, without adding appreciably to the weight of the engine.